https://ogma.newcastle.edu.au/vital/access/ /manager/Index ${session.getAttribute("locale")} 5 https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:12166 Sat 24 Mar 2018 08:12:13 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:20855 Sat 24 Mar 2018 08:02:51 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:20095 Sat 24 Mar 2018 08:00:09 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:28586 18O, δ¹³C and F¹⁴C signatures, respectively. Low and variable concentrations of magnesite, dolomite and calcite represent bedrock carbonate, which has formed during alteration of the serpentinite bedrock before mining and is characterised by moderately high δ¹⁸O, low δ¹³C and F¹⁴C, a signature typical for ‘weathering-derived’ magnesite deposits in the GSB. The carbonate fraction of deep cement samples, collected from 70 to 120 cm below the surface, representing the bulk tailings material at depth, predominantly consists of pyroaurite (Mg₆Fe₂(CO₃)(OH)₁₆·4H₂O) and, despite stable isotope signatures similar to bedrock, contains significant radiocarbon. This indicates that pyroaurite, forming under different conditions as hydromagnesite, may represent an additional trap for atmospheric CO₂ in the Woodsreef mine tailings. The distribution of carbonates and quartz, together with the absence of isotopic mixing trends between bedrock carbonate and atmospheric-derived carbonate, strongly indicates that dissolution and re-precipitation of bedrock carbonate is not a dominant process in the Woodsreef tailings. The cations for carbonate formation are instead derived from the dissolution of serpentine minerals (lizardite and chrysotile) and brucite. The internal standard method and the reference intensity method have been used with X-ray diffraction data to estimate the abundance of the two major carbonate minerals hydromagnesite and pyroaurite, respectively. Considering the formation of hydromagnesite on the outer surface of the tailings pile alone or together with formation of pyroaurite within the tailings pile we conclude that, between 1400 and 70,000 t of atmospheric CO₂ have been sequestered in the mine tailings since closure of the mine 29 a ago. Carbonation rates of 27 g C m⁻² y⁻¹ and 1330 g C m⁻² y⁻¹ are significantly higher than background rates of CO₂ uptake by chemical weathering and demonstrate the potential of passive carbonation of mine tailings as a cost and energy effective alternative for storage of CO₂ in carbonate minerals.]]> Sat 24 Mar 2018 07:37:25 AEDT ]]>